image As Mother Nature blankets the mountains with the cold white stuff, hundreds of thousands of ski enthusiasts head out to the slopes. For most skiers, a day of fun on the slopes is followed by a relaxing evening by the fire or a night about town. Unfortunately, injury cuts the day short for some and ruins the evening and ski year entirely for others. One of the most common injuries is the torn anterior cruciate ligament.

The anterior cruciate ligament, the infamous ACL, is one of four ligaments (the medial collateral, lateral collateral, and posterior cruciate ligaments are the others) that provide stability to the knee joint. Somewhat smaller than the index finger, the ACL can withstand forces up to 500 pounds. Its specific purpose is to guide the tibia (the shinbone) through its full range of motion while providing stability to the knee joint.

Often torn (ruptured) when the knee is severely twisted, angulated, or hyperextended, this injury is among the most common for skiers. Why, you ask? The answer can be found in a rather ironic twist of manufacturing.

In the 1970s, stiffer boots and improved bindings were introduced by ski manufacturers. These products are designed to improve performance and to help prevent fractures of the lower leg by releasing the foot from the binding when stress is applied to the leg and binding. The long boots also help to protect the ankle. However, stress applied to the knee does not cause the binding to release. The result? A much higher incidence of cruciate ligament injuries. The risk may be higher in women: one study suggested that ACL tears are three times more common in female racers than in their male counterparts.

Symptoms

How do you know if you've suffered a torn ACL? The symptoms vary, but three are relatively universal. First, you'll often hear a "pop" when the injury occurs. Second, your knee joint will swell soon after you sustain the injury (within 2-24 hours) as a result of bleeding into the knee joint from the torn blood vessels of the ACL. Third, in addition to being painful, the knee will feel insecure or "wobbly", the result of lost stabilization from the ACL. Although these symptoms are good indicators, physicians will usually x-ray the knee to rule out a fracture. The physician will examine your knee to see if there is instability, but if a definitive diagnosis is still unclear, an MRI (magnetic resonance imaging) may be ordered. In other cases, an arthroscopic examination of the knee may be performed.

Treatment

Unfortunately, the ACL has a relatively poor blood supply. Therefore, once torn, it cannot repair itself. So, if you do suffer a torn ACL, treatment generally proceeds as follows:

Initially, ice, crutches, rest, a compression bandage, and anti-inflammatory medications are prescribed to decrease the swelling. In more severe cases, narcotics may be prescribed to reduce pain. If you have severe swelling, the physician may use a syringe to remove the blood from the knee. Once the swelling and pain dissipate, physical therapy will probably be prescribed immediately to regain motion and strengthen the knee's muscles. The goal is to help the strengthened muscles take over some of the knee stabilization lost as a result of the tear. In addition, a specially fitted brace may be prescribed to help stabilize the knee. This also helps to prevent damage to the cartilage (which can lead to degenerative arthritis) that may occur to a knee after an ACL tear.

In some cases, especially when only a partial tear (sprain) of the ACL is suffered, physical therapy and an ACL brace will be sufficient to stabilize the knee. But if you want to participate in strenuous activities, surgery is usually required.

In the past, open surgery to reconstruct the ACL was performed with success, but the rehabilitation process was slow. Today, surgeons will perform surgery arthroscopically utilizing small incisions. Generally, this surgery entails the following:

  • Small incisions are made around the knee.
  • An arthroscope is inserted, and the ends of the torn ACL are removed.
  • Next, a portion of the patient's patellar tendon (the one that attaches the kneecap to the tibia) or some of the hamstring tendons are harvested as a graft. The graft is fixed into tunnels in both the tibia and the femur (thigh bone) where the ACL was attached.

    This procedure is very effective for skiers and others active in sports, since it uses the patient's own tissue and allows the knee to retain its normal anatomical motion. The knee can heal back to its original degree of strength with a low risk of infection or graft breakage. The reconstruction usually lasts a lifetime, but repeat tears can occur with sufficient stress.

This type of surgery generally requires an overnight stay at most, and in many cases, the patient can leave the hospital the same day.

Following surgery, the patient will generally be referred to a physical therapist for a rehabilitation program that usually lasts about six months. The program, which includes range of motion and strengthening exercises, is designed to increase knee motion and strengthen the muscles around the knee. An ACL brace is generally prescribed for use with any physical activity for at least a year after surgery to help stabilize the knee while it continues to strengthen.

Prevention

Considering the pain, inconvenience, surgery, and the lengthy recovery, your best bet is to prevent ACL injuries from happening in the first place. The best way to do this is to strengthen the muscles surrounding the knee, specifically the hamstrings and quadriceps. The reason? These two sets of muscles are crucial in giving a skier the ability to regain balance and control (such as after you've "caught an edge"), thus preventing the twisting and hyperextension of the knee that can cause the ACL to tear. The hamstrings also control forward motion of the shin bone on the thigh bone so strength of this muscle group is essential.

In addition to general muscle exercises, there are specific thigh muscle exercises designed especially for skiers. One exercise entails bending one of your legs behind your body, then flexing up and down from 30° to 80° on the other leg for three to five minute intervals. Other good exercises include leg presses, squats, bicycling, and stairclimbing.

Exercising the leg muscles is particularly beneficial when performed regularly in the months prior to the start of ski season. In addition, you might consider consulting with a sports physician or trainer to try out other exercises and stretches designed to strengthen your knees and the rest of your body, which will improve your performance and lower your risk of injury.